This invention relates generally and more particularly to using a single triggered dose oxygenator employing an optoelectronic inhalation sensor as an apparatus for inhalation therapy that may be supplied with therapeutic gas from a number of supply sources, such as:
Wall outlet supplying a therapeutic gas (such as oxygen) to a patient in a hospital.
High pressure tank supplying a therapeutic gas (such as oxygen) to a patient at home.
Small tank mounted on a portable cart to be used for portable use.
Oxygen concentrator that manufactures oxygen from ambient air.
This invention also pertains to the apparatus used for measuring and controlling a supply of a flow of therapeutic gas to a triggered dose oxygenator employing an optoelectronic inhalation sensor used for inhalation therapy.
The flow of gas in prior art is normally regulated by using a flowmeter with a variable orifice. In a triggered dose oxygenator using the optoelectronic sensor the flow of gas can not be controlled by a variable orifice for the flow of oxygen is turned on and off by means of an electrically operated solenoid valve. This solenoid valve thus acts as a totally closed or open orifice and makes it impossible to use an orifice as part of the flowmeter for controlling the flow of gas.
This invention overcomes the difficulty by using a variable pressure regulator to overcome this problem of regulating the flow of the therapeutic gas.
An additional function is that a triggered dose oxygenator employing an optoelectronic inhalation sensor is able to trigger a dose of inhalation therapy gas when the optoelectronic inhalation sensor detects inhalation. The dose can be adjusted to correspond to the normal period of inhalation, approximately 30% of the time between breaths, so that no therapeutic gas is delivered during exhalation. This can theoretically save 70% of the therapeutic gas that would normally be used if the therapeutic gas is delivered the full breath time.
Intermittent gas flow has been achieved in the prior art by various means (such as Durkan, U.S. Pat. No. 4,484,578) by using fluidically operated devices, that not only require an electrical power source, but also a gas supply to make the sensor function. The advantages of using an optoelectronic sensor is that it only requires an electrical power source and is more sensitive to the extremely low negative pressure of inhalation and reduces the number of components to achieve lower manufacturing cost.
A triggered dose oxygenator using an optoelectronic sensor also has the advantage over prior art in that a single nasal cannula can be used, not only for sensing, but also for delivering the therapeutic gas.
In the prior art, often two connections to the patient are required; one tube to one nasal passageway to sense inhalation, and a second tube to the other nasal passageway to deliver oxygen.
Another advantage of an optoelectronic sensor over the prior art that uses temperature sensing to detect flow of gases over a heated element is that such sensors are affected by humidity, whereas humidity does not affect an optoelectronic sensor, as it is equipped with an educator that removes the moisture when a dose of oxygen is delivered. In thermo devices where the entire device is on a micro-chip, moisture can destroy the device or cause great inaccuracies in measuring the flow of gases.